Automatic merge from submit-queue (batch tested with PRs 60990, 60947, 45275, 60565, 61091). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.
Support multi-container pod for "kubectl logs"
kubectl logs -l will print logs for pods with the same label, however it doesn't support pods with multi containers. This change adds support to it with --all-containers.
Ussage:
$ kubectl logs my-pod --all-containers
$ kubectl logs -laa=bb --all-containers
$ kubectl logs my-pod my-container --all-containers (err: container should not combined with --all-containers)
**Release note**:
```
add --all-containers option to "kubectl log"
```
Fixes:
https://github.com/kubernetes/kubectl/issues/371
cea4284677